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What you can afford to spend to win one
'Is this ad worth it?' is the wrong question. The right one is: what's the most I can spend to win a customer and still hit my margin? Without that ceiling, every marketing decision is a guess — and some guesses quietly bleed you dry.
Allowable Acquisition Cost is the marketing slice of lifetime value: the most you can spend to land one customer and still hit your target margin. High LTV lets you spend a lot — even lose money on the first sale — because the relationship pays it back. Low LTV means you can spend almost nothing per customer.
- Start with average customer lifetime value — say 2,000 over five years.
- Subtract what it costs to create and deliver the value over that whole relationship — say 500 — leaving 1,500.
- Subtract this customer's share of overhead: total overhead ÷ number of customers (e.g. 500,000 ÷ 500 = 1,000), leaving 500.
- Multiply what's left by (1 − your target margin). For a 60% margin, multiply by 0.40: 500 × 0.40 = 200.
- That 200 is your ceiling. Any channel that reliably wins a customer for 200 or less is worth scaling; anything above it loses you money.
Your customer is worth 2,000 over five years. Delivery costs 500, and each customer's overhead share is about 1,000, leaving 500. You want a 50% margin, so you can spend half: 250 per customer. A 100 ad that wins one customer is a bargain; a 400 one is a slow leak.
Proactiv sold acne cream through expensive celebrity infomercials at a first-sale price of about 20 — deliberately losing money on that first order, because every buyer was auto-enrolled in a monthly subscription whose lifetime value dwarfed the loss.
→ Because the high LTV made a money-losing first sale enormously profitable overall, Proactiv became one of the best-selling acne brands in the world, reportedly exceeding a billion in annual sales at its peak.
The model only works if cancellation is honest and easy. Proactiv's auto-ship billing generated heavy complaints about hard-to-cancel recurring charges and regulatory scrutiny; sales later declined and the brand changed hands. Loss-leader-plus-subscription is powerful but breeds lawsuits when the exit is a trap.
The opposite mistake is buying sales at a loss with no lifetime value to recover it. As the saying goes, that's no smarter than standing on a corner handing out twenty-dinar bills until you go broke. Volume is worthless if each sale loses money and nothing comes back — acquire only below your ceiling.
Never approve a marketing spend by gut. Calculate your Allowable Acquisition Cost once, then judge every channel against it: under the ceiling, scale it; over it, kill it — no matter how exciting it looks.
Using your lifetime-value number from the last lesson, subtract delivery cost, overhead share, and your margin to get one ceiling figure. Then look at your current marketing and flag anything costing more than that per customer.
When can a business afford to lose money on the very first sale — and what number tells you the absolute most you may spend to win a customer before you're just handing out cash?
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